Such a mower is known comprising two mowing groups the cutting bars of which are aligned and placed crosswise to the direction of work so as to form a uniform cutting front. The two cutting bars are connected to one another by one or two cylindrical joints with a geometric axis at least approximately parallel to the direction of work. The two cutting bars comprise rotary cutting elements which are driven in rotation by a separate belt transmission for each cutting bar. The power necessary during work transits via a transmission housing surmounting the outermost rotary cutting element of each cutting bar and is then distributed to each rotary cutting element of the corresponding cutting bar by transmission elements housed on the inside of the housing of the cutting bar. This may be accomplished, for example, by toothed wheels that mesh with one another and on the shafts of some of which are mounted rotary cutting elements. This makes it possible to improve somewhat the qualities of the cutting of a mower of great width in rough terrain, but especially makes it possible to increase the reliability of the mower because the bending forces to which the two cutting bars of the known mower are subjected when it works in rough terrain are slighter than if the mower comprises a single cutting bar of the same work width.
In practice, it has been shown that the degrees of freedom possessed by each mowing group of this known mower are, however, insufficient to assure a maximum adaptability of the machine to the most marked reliefs of the terrains where this type of machine performs.
Another mower is known comprising a mowing group comprising, on the one hand, a cutting bar equipped with rotary cutting elements and, on the other hand, a carrying structure. The carrying structure of the cutting bar is connected to the chassis by a pulled parallelogram device. The pulled parallelogram device comprises three connecting rods: an upper central connecting rod and a lower connecting rod at each end of the mowing group. The pulled parallelogram device makes it possible to maintain a constant stable position of the cutting bar in relation to the ground. In addition, the pressure on the ground produced by the weight of the mowing group that rests there is reduced by a compensating system of springs. The combination of these two means makes it possible to obtain a good adaptability of the mower to the relief of the terrain on which it performs.
On the other hand, since the cutting bar is in a single piece, the qualities of the known mower become blurred as soon as the work width of the machine is increased. This is due to the fact that, when the cutting bar made in one piece encounters an obstacle at any spot on its width, the entire cutting bar moves to overcome this obstacle. Accordingly, the cutting quality of the known mower becomes unacceptable for the users beyond a certain work width.